On January 18, Beijing added one case of asymptomatic infection in a 9-year-old boy, and on January 20, a press conference on prevention and control in Beijing introduced that nasopharyngeal swabs, oropharyngeal swabs, anal swabs and serological tests have been conducted on all students and staff at the school where the case is located, and 1298 people have been sampled, with 5192 samples collected.
The most common sampling method is the pharyngeal swab, Daxing how also increased the anal swab test? Many people are confused about this.
Liang Lianchun, director of the infection department at Beijing Youan Hospital, told the health Times that the increase in anal swab testing could improve the detection rate of virus-infected patients to a certain extent.
Liang Lianchun introduced that it is not uncommon for anal swabs from patients with CCP to show positive nucleic acid tests, suggesting the possibility of fecal-oral transmission of the disease. The early stage of the disease is dominated by positive nasopharyngeal/oropharyngeal swab nucleic acid, but some patients, especially those with intestinal symptoms as the main manifestation, may also have a positive anal swab nucleic acid, or even a positive anal swab test may precede the nasopharyngeal swab; and in a small number of cases, the anal swab nucleic acid continues to be positive even after the clinical symptoms improve and the nasopharyngeal/oropharyngeal swab nucleic acid turns negative at a later stage of the disease These cases may be related to the presence of neocoronavirus in the nasopharynx. The above situation may be related to the different target organs mainly invaded by the new coronavirus in different individuals and the special environment of the intestinal tract.
In March 2020, the clinical research team of Guangzhou Women’s and Children’s Medical Center published a paper in Nature Medicine on “Epidemiological and clinical characteristics of children with neocoronavirus infection and exploration of evidence for sustained intestinal detoxification”, which found that positive anal swab nucleic acid tests persist for a longer period of Time in children, with the possibility of fecal-oral transmission.
“From clinical statistics, the maximum duration of pharyngeal swab detoxification in children is more than two weeks, and most of them turn negative in three to five days, but the duration of positive anal swab test is sometimes longer, and the longest case found can be more than seven weeks.” Xu Yi, director of the infection department at Guangzhou Women’s and Children’s Medical Center, had said in an interview.
However, Liang Lianchun said that in general, if the anal swab tests positive for new coronary nucleic acid, there are two possibilities: one is the presence of live virus in the patient’s intestine; the other is that the detection is a fragment of the degraded nucleic acid of the virus. Some patients in the late course of the disease, symptoms significantly improved, pharyngeal swabs negative, but anal swabs continue to be positive, may only detect nucleic acid fragments, does not amount to the continued discharge of active virus through the feces, whether it is infectious need further in-depth study; but if in the digestive tract symptoms are more obvious early in the disease, anal swabs positive new crown nucleic acid, it is a different story.
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